HMOX1 and atrial fibrillation: Table 3 displays the baseline characteristics of these 16 patients. The HO-1 expression in myocytes (identified by co-localization with α-actin) was greater in the atria of AF patients homozygous for short repeat alleles than that homozygous for long repeat and SR controls, although AF patients homozygous for long repeat alleles still had higher HO-1 levels than SR controls (Figure 1).